[noun] A dark-colored intrusive igneous rock that consists mostly of the minerals plagioclase, pyroxene, and olivine. Gabbro has a similar composition to basalt, which is extrusive. Both gabbro and basalt are mafic rocks, composed of minerals high in iron and magnesium.

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[person] The Italian physicist, mathematician, and astronomer born in Pisa in the Grand Duchy of Tuscany (1564-1642 CE). Among other things, Galileo studied the acceleration of objects and discovered the four largest moons of the planet Jupiter. His work significantly advanced the use of quantitative experimentation in science, and he made noteworthy contributions in the development of technology: He invented the refracting telescope, perfected the compound microscope, and improved compass design. Galileo was famously jailed during the Inquisition for his support of Copernicus's heliocentric view of the cosmos.

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[noun] The state of matter characterized by its non-condensed nature and ability to flow. Unlike liquids, molecules within a gas remain far apart from each other and show little interaction with other molecules. Unlike solids, gases do not have fixed shapes and take the shape of their container (as do liquids). Compare with liquid and solid.

[noun] A physical constant used in the ideal gas equation to relate a gas’s state to its pressure, volume, amount, and temperature. Given the symbol R, it was first defined by the German chemist August Horstmann in 1873.

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[noun] Active ion channels can regulate the passage of ions via a gate mechanism. Gates can open (allow ions to flow through) or close (restrict the flow of ions) depending on external signals. This property of permitting and restricting ion flow is called "gating."

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[person] German mathematician born in Brunswick, Germany (1777 – 1885 CE). Sometimes called the “prince of mathematics,” Gauss made important contributions to many fields of mathematics and science. In his major 1809 work Theoria motus corporum coelestium, Gauss presented several mathematical approaches for addressing the experimental measurement errors that plagued astronomers of the time. These included the method of least squares and a mathematical derivation of the normal distribution.

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[person] A French physicist and chemist, born in Saint-Léonard-de-Noblat, France (1778 – 1850). Gay-Lussac performed extensive research into gases, which influenced the work of the Italian chemist Amedeo Avogadro and the development of Charles’s Law after the French scientist Jacques-Alexandre-César Charles.

[noun] The intentional use of any technique to expand, or drive, particular genes and their associated traits through a population of sexually-reproducing organisms. This results in the particular genes being passed to offspring at rates higher than what Mendelian laws would predict.

[noun] Also referred to as General Climate Models; a class of computer models used for weather forecasting and understanding or projecting climate change. GCMs designed for applications with the scope of decades to centuries were originally created by Syukuro Manabe and Kirk Bryan at the Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey. For more information, see our module Modeling in Scientific Research.

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[noun] The genetic makeup of an organism or group of organisms; the genetic description of an individual. Genotype may refer to a single gene, a set of genes, or the entire genetic makeup of an individual.

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[noun] (GIS) A set of computer-based tools used to collect, store, analyze, and map data that has a location-based or spatial component, such as latitude and longitude. The term GIS usually includes computer software and hardware, data collectors, and the data itself.

These systems allow researchers and decision makers to compile information from many different sources. By gathering and mapping a wide variety of data, we can see new trends and relationships. Satellite images, records of soil type or vegetation cover, census data, locations of roads and schools, and many other types of data can be compiled in a GIS.

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[organization] A professional society established in 1888 focused on geosciences. The mission of the Geological Society of America is "to be a leader in advancing the geosciences, enhancing the professional growth of its members, and promoting the geosciences in the service to humankind and stewardship of the Earth." GSA hosts an annual meeting and several section meetings every year and publishes several journals. More information about GSA can be found at their website: http://geosociety.org

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[person] American geologist born in Rochester, New York (1843-1918). Gilbert participated in the Wheeler geologic survey of the American West. His field studies resulted in the publication on The Geology of the Henry Mountains, which established his preeminence as a geologist. In 1879, he was appointed the Senior Geologist at the newly created US Geological Survey. In addition to his study of the Henry Mountains, Gilbert investigated the Pleistocene Lake Bonneville. He is considered a major founder of the field of geomorphology, having investigated and published on erosion, river incision and sedimentation.

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[noun] (GPS) A system of satellites maintained by the US government that provides people with highly accurate information about their location on Earth (within about three meters) and how to navigate from place to place. Users obtain the information (called coordinates) using GPS receivers, such as handheld devices, navigation systems in cars, and programs like Google Maps.

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[person] English primatologist and anthropologist, born in London (1934-). Goodall is famous for her ground-breaking 45-year study of chimpanzee family and social interactions in the Gombe Stream National Park, Tanzania. She founded the Jane Goodall Institute and remains a leader in global efforts to protect chimpanzees. Goodall revolutionized the field of primatology by discovering tool-making among wild chimpanzee populations, and remains the only human ever accepted into chimpanzee society. Interestingly, Goodall suffers from prosopagnosia, a neurological condition that makes it difficult for her to recognize human faces.

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[person] (1886-1949) An American chemist and science educator. Gordon is most famous for his dedication to communicating science. He founded and was the first editor of the Journal of Chemical Education, published by the American Chemical Society, and established the Gordon Research Conferences, a venue to bring scientists together to discuss research on the frontiers of knowledge.

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[person] (1876 - 1937) Gosset was a chemist working for the brewery company Guinness and the developer of "Student's t-distribution" tool. Gosset needed a way to select the best varieties of barley to use in Guinness’ beer by analyzing only very small subsamples of data collected from the farm. After studying with Karl Pearson, Gosset developed the Student's t-distribution, a new mathematical tool that could be used to estimate a population mean based on a small subsample.

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[person] American paleontologist born in New York City, New York (1941-2002). With Niles Eldridge, he co-created and championed the concept of evolution via punctuated equilibrium, and wrote many popular books about evolution, paleontology, and the history of science.

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Scottish physical chemist (1805-1869) born in Glasgow. Graham first quantified the principles of diffusion by studying gases passing through plugs, tubes, and small openings. His research resulted in Graham's Law, which states that the rates at which two gases diffuse is inversely proportional to the square root of their densities.

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[noun] A light-colored, coarse-grained igneous rock formed by cooling of silica-rich magma below the surface of the Earth. Granite is considered to be the average composition of the continental crust of the Earth.

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[noun] The greenhouse effect is created by gases like carbon dioxide in the Earth's atmosphere. Carbon dioxide and other greenhouse gases allow radiation from the sun to pass through the atmosphere; the Earth then absorbs this radiation and emits heat. That heat is absorbed by the greenhouse gases, resulting in atmospheric warming.

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[noun] A greenhouse gas is a component of the atmosphere that absorbs heat radiated by the Earth and subsequently warms the atmosphere, creating what is commonly known as the greenhouse effect. Common greenhouse gases include carbon dioxide (CO2), methane (CH4), water vapor, and sulfate (SO4).

[person] (ca. 1879 - 1941) A British microbiologist whose research focused on the epidemiology and pathology of bacterial infectious diseases. In 1928, Griffith published his most famous paper, which contained the first widely accepted demonstrations of bacteria changing form and function. His experiments showed the bacteria Streptococcus pneumoniae transforming from one strain to another. His findings encouraged other researchers to try to identify the mechanism by which this change could occur; eventually this research led to the discovery of DNA.

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[verb] To gather data onsite in order calibrate a model or determine whether information captured remotely (such as imagery or measurements taken by satellite) is being accurately interpreted. This often involves going to a location "on-the-ground" or in the field to compare actual characteristics, such as vegetation cover or temperature readings, with characteristics predicted by a model or interpreted from an image. This technique is commonly used with aerial and satellite imagery, remote sensing, meteorology models, and GIS.

[noun] Data collected at a study site, as opposed to information collected remotely or predicted by a model.

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[noun] Water that fills pore space in rocks and sediments and forms a subsurface aquifer. Groundwater is distinct from soil moisture, which does not completely fill pore spaces and is immediately beneath the surface.

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[person] German geophysicist, born in Darmstadt (1889-1960). Gutenberg is best known for precisely determining the depth to the core of the Earth and describing its elastic properties. He also described the differences in structure of oceanic and continental crust, discovered a low-velocity zone within the mantle, created a magnitude scale for earthquakes, and studied the distribution of temperature in the Earth.